A Vow of Eternity
by Infinite Skye
Summary: Kuroko Tetsuya was branded a traitor of humanity, accused of being a titan in a fear-ridden society. In an attempt to flee the city, he met a man with passionate red hair, yet eyes of the dead. "Will you serve under me for the sake of humanity?" Akashi-shichou asked, as though he was waiting, for a long long time. And thus, were the beginnings of a vow of eternity. Akakuro SNK AU


**Gift fic for Mademoiselle Z!**

* * *

In the midst of falling rain, drizzling upon the densely matted aggregate of trees, a lone man stood, red hair dripping wet from the rain as his heterochromatic eyes of a passionate red and gold fell onto the bloodied body of a male.

The male had his once gorgeous azure blue eyes closed, face peaceful as though he was in slumber...but the the red-head knew better.

Promptly, he took out a blade, long and sharp, perfect for killing titans. Yet, instead of plunging it into said monsters, with a single pause, a hint of hesitation, he stabbed the blade into the blue-haired man.

There was no reaction from the dead man.

His eyes, were closed, face peaceful and lifeless, as though all signs of pain, proof that one was alive had escaped him.

But slowly, blood oozed out of his lips, a red passionate crimson, the proof of life in a dead man's body.

The red-head stared, hair filled with the symbol of life the dead man lacked as his eyes grew bitter, resembling ones of the dead.

He parted his plump, red lips.

"Ah, again, I lost my chance to tell you, just how much, I've always loved you."

[=]

On his back, carried perfection.

That was Kuroko's first impression of Akashi Seijuro as he was hoisted out of a titan whose limbs had somehow become his, out of breath and dazed, azure irises tiredly falling onto the unwavering back of an unfamiliar red-head, cape billowing in the afternoon sunset.

"Who?" His friend and fellow trainee Ogiwara Shigehiro squinted before the red-head turned, revealing a pair of beautifully dangerous heterochromatic eyes.

"Kuroko Tetsuya and Ogiwara Shigehiro correct? I'm here to retrieve you two," Akashi stated, striding towards them with an air of elegance, in spite of the blood that had clung to his uniform, staining it with the same red as his hair.

"...You're here to retrieve us...so you can lock Kuroko back up in a cell and call him a monster again?" Ogiwara frowned as Kuroko slightly flinched, reminded of the very reason the two had escaped from the walls.

_What is that? He can change into a titan? Isn't he a titan then. pretending to be human?!_ The whispers of horror suddenly buzzed in his ears once more as Kuroko narrowed his eyes in pain.

This was why he shouldn't have taken Ogiwara's hand and escaped from the cell. This was why he shouldn't have allowed his childhood friend to leave the walls with him, shouldn't have bought his story of a secret village call Meikou that lived perfectly fine outside the walls of Teikou.

After all, their operation was a complete failure. Even when Kuroko managed to tranform into a titan, no more accurately, _infect _a titan, he could not be among the other titans that craved for human flesh. They didn't manage to get far at all before they were stopped and...almost killed.

Kuroko slowly eyed the wound on Ogiwara's arm and bit his lip. Perhaps he could somehow ask this man to spare Ogiwara's life.

"Ogiwara-ku-"

"...Oh? Who ever said I was going to do that?" The red-head began, raising a brow at Ogiwara's statement as the two blinked up in surprise.

"Eh?"

The red-head smirked. "Certainly, Kuroko Tetsuya cannot be considered normal." He continued, eyes carefully inspecting the blue-haired teen.

Ogiwara instinctively tensed.

"However, the abnormal is exactly what humanity requires to win against the titans. Those incapable of this will not survive. When considering how you two managed to break out of the court prison as well as run this far away from the walls, I must credit you two for exceeding my expectations towards humanity," Akashi concluded, as if praising them in an extremely indefinite way.

Yet, the two who were segregated because of Kuroko's abnormality, were both rendered speechless.

"...Who are you?" Ogiwara asked, echoing Kuroko's thoughts.

The red-head released a smile. "I am Akashi Seijurou, Heishichou of the Survey Corps. And, from today on, the two of you shall serve under me...for humanity's sake."He declared, voice particularly placing emphasis on the word humanity.

Yet, the fact that he was willing to protect an otherwise deemed worthless race, should've been the first clue to his true aims.

Kuroko didn't know a thing back then, nothing at all...and, his first mistake, was being pried away from his childhood friend, smoothly and naturally, that he didn't notice a thing.

[=]

Just like Akashi-shichou had reassured, the trial after the two were forced back when well. Under the statement that Kuroko Tetsuya was indeed not a titan but someone with special cells that can infect a titan and control them, he was an invaluable presence to have for humanity's survival.

Akashi-shichou led the defense himself, speaking with such confidence that the counter sounded like quacks attempting to dig up a non-existant rebuttal. However, just as soundly, he also stated that Kuroko was to stay under his squad's surveillance, while Ogiwara Shigehiro was the return to the trainee squad and choose between the Military Police, the Wall Police, and the Survey Corps.

There was no doubt in what he had chosen yet, because of the high levels of Akashi's special "Miracles" squad, he was unable to meet with Kuroko regularly. However, because of their sudden distance, little did he know that Kuroko was already entrapped, by the colorful personalities of humanity's strongest soldiers: the Generation of Miracles.

"Hey Midorimacchi, when do you think we'll be able to get out of this place? I'm bored," Kise Ryouta, the soldier of 100 kills, sighed in attempt to make conversation as the rather silent members of the group sat in the dining hall, sipping on some gruel.

"That is unlikely since I haven't even completely half of my research yet. Moreover, I've already told you many times to stop calling me so familiarly," Midorima Shintarou, the soldier and scientist of the group scowled.

"Ara~? Are you depressed Mido-chin? See, I told you Kuro-chin definitely wouldn't be useful~" Murasakibara Atsushi, the "titan" of the group reminded, a bit of malice layered under his light-hearted tone.

Midorima immediately shot the soldier a glare.

He was supposedly in charge of thoroughly investigating Kuroko's special ability despite him coming from a rather normal upbringing in consideration to their standards. He did many things, exposing Kuroko to a captured titan and as if he was not there at all, the teen easily disappeared before appearing inside the being, now in complete control once he came in contact with the base of said titan's neck.

However, when asked to attempt to change with another body part, nothing happened at all. Now really, it was due to Midorima's lack of consideration towards human subjects, as this was indeed a first for him, having to research a person he must have actual conversations with, but regardless, he was still miffed.

Kuroko, who had spent his time in silence suddenly released, "sorry that I wasn't very helpful Midorima-san. I'll do my best to be more of use next time."

Midorima was about to burst. THAT WAS THE PROBLEM! The fact that he was apologizing despite it not being his responsibility only made Midorima feel worse. Yet, his pride couldn't allow him to say one word of reassurance.

"No, it was-"

"Kuroko wasn't at fault. Shintarou's experiments were too impartial." A crisp clear voice said as all eyes swept towards the door, where a red-head stood, followed by a yawning swarthy male.

"Mhn? Ah, Aka-chin, Murasakibara greeted, acknowledging their captain.

Kuroko did so accordingly as Akashi gave him a curt nod. Since arriving at the survey corps, Akashi had not given him too much attention compared to the rest but for some reason, the look in his eyes whenever those sky blue irises meet red and gold, seemed to say a thousand unspoken words. It was a strange feeling, manipulative almost but nevertheless, it got Kuroko to trust in Akashi, who always believed in his capabilities.

Midorima sighed. "With such minimal data regarding the nature of titans, experiments have still proved to be hard to conduct in a fashion that would benefit mankind."

"Ah? Oi, don't tell me you guys are still disapproving of Tetsu," a low voice questioned as through the doors of the hall sauntered in a dark-skinned male that radiated sun.

"Eh, Aominecchi is early today," Kise commented while the rest of the group gave some form of acknowledgement respectively.

"Ah? Is there something wrong with that?" Aomine Daiki, the ace of Akashi's squad challenged.

Kise furrowed his otherwise beautiful face. "No but, something else is wrong. What do you mean by disapproving of Kurokocchi? We obviously approve of him, I mean, Kurokocchi is amazing! You can help us in so many ways by turning into a titan!" Kise exclaimed brightly at the youth.

"Eh? But still, Kuro-chin can't completely control his powers, we don't know what if he'll always stay on our side," Murasakibara refuted, slightly miffed at Kise for forcing his opinion on them.

"I completely agree," Midorima added, "you should be more wary Kise, or else you'll lose your life fast," he sighed.

Kuroko immediately tensed. As he thought, it was impossible for others to so easily accept them.

"Ehh~ but it's fine, I've never managed to fail a mission yet so it's all good~" Kise brightly returned.

Midorima blew. "DIDN'T I JUST SAY THAT TYPE OF THINKING IS EXACTLY WHAT MAY CAUSE YOU TO DIE?!"

Kise paused for a moment, before widening his eyes in astonishment. "...Eh? Does this mean...you're _worried_ Midorimacchi?'

"...HAH?!" Midorima cried as a huge banter erupted from him, Murasakibara joining in on the rare sport of teasing the stoic male.

Kuroko had to remind himself that technically he was the youngest, at 16 years old, while the others were at least 3-8 years older than him. However, he didn't feel as though he was conversing with legitimate adults whatsoever. But, then again, what was an adult in this world?

Such a title was barely worth a cent in a twisted world like this.

Yet beside the trio, he found Akashi, calmly sipping on tofu soup.

A slight bit of respect returned for the adults.

"Oi Tetsu, are you planning on doing extra training today too?" Aomine suddenly inquired while nonchalantly taking a seat beside the teen.

"Ah, yes of course. My training was cut-off after all since they had to force even the trainees to fight in that battle," Kuroko stated, recalling how they had 6 more months left of training before they were allowed to become official soldiers.

However, because the titans invaded the wall of Trost, this was abruptly halted and immediately afterwards, Kuroko had unfortunately spent the remaining 6 months locked up in a cell after he somehow transformed into a titan for the first time. It was a miracle they didn't attempt to dissect or torture him to death but regardless, he still ended up quite weak, thus requiring additional training.

"Ahh, geez the big officials of this place. Well I'm glad they didn't kill you on the spot but still, lock you up for 6 months? I can't tell if they're just plain stupid or not," Aomine commented in strange sympathy before Kuroko released a curt smile.

It seems that in the end, he got along with Aomine Daiki best. He was the reliable ace who would always encourage him, help him whenever Kuroko had trouble completing some of the physical maneuvers. Despite being able to turn into a titan, physically Kuroko was of weak-build, how he survived the trainee squad for 3 and a half years was surprising even for him.

Perhaps it was because of Ogiwara, the childhood friend that had always been beside his side since young. He felt a bit nostalgic and worried, wondering how he was doing but upon sharing a bit of himself to Aomine at least, he learned that Aomine had someone similar-a childhood friend named Momoi Satsuki.

Kuroko met her once. She was part of the Military Police. She had vibrant pink-hair tied into a neat bun, a highly skilled soldier who helped greatly in the battle of Trost, plowing on with strategic advances despite watching many of her soldiers die. There was a fond air when Aomine spoke of her, as if he was proud in a sense before then continuing on about how annoying she was. Yet, that in the end was still proof of how strong their bond was.

It made Kuroko unable to question why they decided to part from each other out of their own volition. Even to this day, he didn't know if he would've been able to but regardless...he felt he should've asked something...so things didn't have to turn out _that_ way.

[=]

It turns out that there was someone much more vocally capable of giving heart-felt speeches than Akashi, as on the day of the 57th expedition, commander of the survey corps, Nijimura Shuuzo concluded his speech with a ringing, "and offer our hearts to humanity!"

It was not his words that struck every member of the team but rather, his _eyes:_ bottomless, black, and brimming with passion. He believed in the cause, was willing to sacrifice everything for a better world, something that touched Kuroko, allowed him to recall why he enrolled in the trainee squad in the first place, and become ashamed of his attempt to escape.

Yet, little did he expect that the Generation of Miracles, would look fired up as well as every single one narrowed their eyes, determined for victory. They were generally quite relaxed after all.

With a deep breath, Kuroko did the same, heightening his focus as he got onto his horse, protected on all four sides by the Generation of Miracles, with Akashi Seijuro's unwavering back in front.

It was the day of their first expedition together and naturally, Kuroko's life was to be protected at all costs.

Suddenly, his captain turned as once again, those heterochromatic eyes spilled into Kuroko. "Kuroko, are your preparations complete?" Akashi-shichou asked.

Kuroko nodded. "Yes."

He smiled. "Then good. I'll be counting on you."

And somehow, Kuroko widened his eyes, not because it was the first time Akashi-shichou made such a gentle expression towards him, nor was it because he was placing his faith in him, but rather, inside Kuroko, there was a feeling of anxiety, ghosting down his neck.

Eh? Didn't something like this happen once before? Once...long long ago?

His question was pushed aside once the gates of the city opened, Kuroko's eyes widening in awe.

On the other side, revealed the freedom, he and Ogiwara had once sought for.

It was said that this was an expedition to capture a small town with many valuable resources intact. Yet, in truth, it was an operation...to sniff out a spy within the group.

How did this come about? All because of a few words Akashi, the one who had never failed to make a right decision, uttered one day,

"_Shintarou, you stated we didn't have enough data on titan-shifters to learn more correct? Well then, how about we find one...other than Kuroko Tetsuya?"_

And on that day, quite coincidentally, the titans they were experimenting on with Kuroko were promptly killed.

Akashi predicted that it was an enemy, one that wanted to prevent further development of Kuroko's titan form. And who would do that? Naturally people who knew its secrets, and didn't want more to be exposed.

In other words, the titan shifters.

[=]

If there was anything Kuroko learned from being in the survey squad, it was that Akashi-shichou's orders were right,_ always_ right that even with a 13 meter class titan chasing after them, not a single one of the squad members wavered, galloping on horseback as they attempted to slow the titan off by pelleting it with fellow soldiers whose screams sent chills down Kuroko's ears.

He had to help them. He _had to.__  
_

"Don't look back." Akashi repeated, just before Kuroko was about to voice a complaint. As long as he could contact that titan, he would definitely be able to assimilate it.

"Don't worry, Kurokocchi, Akashicchi has never been wrong before!" Kise reassured, yet eyes still hardened in concentration as they plowed on.

Kuroko clenched his teeth, complying before suddenly, a barrage of bangs resounded in the air, all 6 of them immediately halting as they reared around, to find the titan skillfully covered from head to toe, in grapplers that dug deep into its flesh, rendering it unable to move.

"T-this is..." Midorima began in astonishment.

Kise whistled. "Wow, as expected of Akashicchi! He really did manage to capture it!"

"Naturally." Akashi replied, dismounting his horse as he waved Kuroko over. "Well then, Kuroko, I'll have you join me in unmasking the one within." Akashi smirked as Kuroko nodded, ready to perform his duty.

Landing soundlessly on the titan with midnight black hair, the face of a female, and the body of a male, Kuroko sucked in a deep breath and closed his eyes. Hypothetically, since he could take over a titan by contacting them, it should've been possible for the same to occur despite dealing with a titan shifter.

However, as said titan had its hand covering the base of its neck, Kuroko had to settle for the part slightly above the base, concentrating fully on what he had to do.

It seemed that in the end, he did want to be useful to humanity. He grew up in a normal family within Trost. He lived a normal life, indulging himself in books before one day deciding to join the trainee squad along with Ogiwara. Ironically, that was done on a whim, because Ogiwara's passion towards no longer being afraid, going to see the outside world was astonishing.

It made Kuroko wonder, if someone as normal as him, as transparent as him could make a difference as well. He was once invisible...and now, he was crucial, a role he definitely wanted to fulfill to the soldiers that lost their lives, to _his_ squad, and...to Akashi Seijuro, who came him this chance, this place to be.

He closed his eyes, picturing the connection of his limbs, body, like a shadow, sinking into the titan before all of a sudden, he reached something-a wisp of gorgeous pink hair.

"NO!"

And in that instant, Kuroko came face to face with a girl he had never met before-but knew so well that it was almost heart-breaking as he saw all the tears that had slid down her wan face, streaked with grief.

Yet, he wasn't able to do anything for her, nothing at all.

In the next instant, someone was thrown out as he was sucked into the warmth of the titan, eyes now those of the female but shut tightly closed, unable to see a thing as he vaguely heard the scream of "SATSUKI?!", filled with betrayal and disbelief.

Yet, that was the last thing he heard before someone, cut him out, the pain mind-numbing as he slowly lost all control of his senses.

"Sleep" A stern voice ordered, and he did, carried out of the crumbling body by a certain red-head.

However, that was the worst decision he had ever made.

When he awoke, Momoi Satsuki was dead.

She had attempted to escape and Aomine had chased after her.

At the command of Akashi as they saw how she seemed to have gained enough energy to transform again, Aomine Daiki, her childhood friend of all their lives struck, because it was for the sake of "humanity".

Yet, there was nothing human about Aomine's eyes at all.

All Kuroko saw once he awoke, were the eyes of the dead, cold and uncaring.

They resembled Akashi's.

* * *

A/N: Okay I admit. At first it was just supposed to be a simple snk au one-shot for the lovely mademoiselle Z but that kinda spiraled out of control into a full romance/mystery fic because wow my brain is weird so if you're interested in a more plot-focused, tragic romance type of psychological akakuro fic, please carry on.

If you're more in to fluff, well you're gonna have to be patient with me. Like REALLY patient.

I hope you enjoyed this fic!


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